Another issue now fixed was one that could have allowed someone using a malicious Game Center app to access a player's email address. And one flaw that has been fixed had made it possible for a hacker to send email that would appear to come from someone listed in the iPhone owner's contacts list.
The entire list of security updates made by Apple can be found by clicking on the sourcelink. Each listing also mentions the original issue that Apple repaired with the update.
source: AppleSupport via FierceWireless